Radio receiver



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TRn/VaAT/OA/ Feb. 28, 31950 Filed May 24, 1943 INVENToR. 00A/Am o.G/P/EG BY A i ad

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we; w/ T j r lb V45 y 49 Patented Feb. 28, 1950 RADIO RECEIVER Donald D.Grieg, Forest Hills, N. Y., assignor to Federal Telephone and lRadioCorporation, Newark, N. J., a corporation ofDelaware ApplicationvMay 24,1943, Serial No. 488,179

12 Claims. (Cl. Z50-20) This invention relates to radio receivers andmore particularly to a radio circuit for receiving vcarrier wavesmodulated according to different principles of modulation.

Currently there are two principles of carrier wave modulation commonlyused yfor public broadcasting systems. One is A. M. (amplitudemodulation) and the other is F. M. (frequency modulation). Besides thesetwo principles of modulation there are others which are being used inultrahigh frequency systems of communication and in television. Of thesemore recent principles of modulation T. M. (time modulation), which maycomprise either single, double pulse or pulse width modulation, israpidly becoming more and more important. "Single pulse modulationinvolves the transmission of intelligence by variation in the repetitionrate of the pulses. "Double pulse modulation conveys intelligence byvariation in the time interval between pairs of pulses. Pulse widthmodulation conveys intelligence by variations in width of successivepulses or alternate pulses with respect to lxed or pilot pulses.

In view of these several different principles of carrier wavemodulation, that is, A. M., F. M. and T. M., it is an object of myinvention to provide a radio receiver system for receiving andtranslating the intelligence of carrier waves modulated according to anyone of a plurality o such modulating principles.

Another object of my invention is to provide a method and means fortranslating the modulation characteristics of a carrier wave modulatedaccording to any one of a plurality of different modulating principlesinto a substantially equivalent train of time modulated impulses.

These and other objects of my invention I ac'- complish by providing aradio receiver having a detector for detecting carrier waves modulatedaccording to any one of a plurality of different modulating principlessuch as A. M., F. M. and 'I'. M., a translating circuit by which acharacteristie of the detected wave conveying intelligence is translatedinto ypulses having time displace ment corresponding substantially tothe intelligence carried by the wave, and a demodulator for demodulationof the time displaced pulses for audible reception. l

By carrier wave I have reference to forms of carriers havingcorresponding frequency range, whether or not the principle ofmodulation is A. M., F. M. or some formof pulse modul-ation. Thesecarriers may be transmitted in any desired manner.

Te@ translate ,feature ,Q1 the :pratica-1S.

arranged that regardless of the principle of modulation of the detectedcarrier, a suitable translation is obtainable. In some instances. atuning of the translator or certain stages thereof may be required toobtain the optimum quality of reception. The translator, however, iscapable upon reception of a carrier or sub-carrier wave to translate thewave into a form of T. M. pulses which will produce an intelligiblesignal the quality of which may then be improved by proper tuning of thetranslator and/or the demodulator.

For a more complete understanding of the. invention, reference may behad vto the following detailed description to be read in connection withthe accompanying drawings, in which:

Fig. 1 is a block diagram of a radio receiver in accordance with myinvention;

Figs. 2 and 3 are graphical illustrations showing .the steps oftranslation for carrier Waves modulated accordingvto the principles ofamplitude modulation and frequency modulation, respectively.

Figs. 4, 5 and 6 are graphical illustrations showing the depth oftranslation for carriers in the form of a series of pulses representingdouble pulse time modulation, :a form of pulse Width modulation withalternate fixed pulses and another form of pulse width modulation withvariations occurring in successive pulses.

Referring to Fig. 1, a radio receiver is shown according to my inventioncomprising the usual 'R. F. detector stage I0 coupled to an antenna I2plished by means of two limiters connected in series. The clippinglevels, of course, are preferably adjustable for obtaining that portionof the input wave having a characteristic conveying in substantiallylinear proportion the intelligence .with which the wave is modulated.This double ylimiting operation produces a trapezoidal wave form when anamplitude vmodulated or frequency modulated carrier wave is applied tothe gate clipper.

vThe blocking ortrigger oscillator I9 may be of various knownjorms, forexample, it may be a.

spacing of the pulses.

of E. Labin and myself Serial No. 488,183, filed May 24, 1943, nowPatent No. 2,419,570, issued April 29, 1947. It will be understood, ofcourse, that many forms of pulse dividers or pulse blocking systems maybe used for this purpose.

If desired, as hereinafter described in more detail, the oscillator maybe cut out of the circuit by manipulation of the switch ISa. Whenswitched to connection |9b, the oscillator I9 is by-passed and whenswitched to connection |9c,

the pulse-.energy is rectified and mixed at 24 thereby making thenegative and positive input pulses unidirectional. Device 24, forexample, isa well-known rectifier and amplifier arrangeyment whereby theinput pulses are first rectified and then mixed in an amplifier withunrectied input pulses, the amplifier having cut 01T' characteristicssuch as to limit the output thereof to pulses of a given polarity asillustrated, for example, in U. S. Patent Nb. 2,061,734, grantedNovember 24, 1936.

The output pulses of the'translator i4 are applied to-the T. M.demodulator for demodulaytion of the intelligence conveyed by thedisplacement of the pulses. While the demodul-ator 20 may be of.various: constructions such for example as disclosed in U. S. Patent No.2,266,401 it preferably is of the character disclosed in my copendingapplication Serial No. 459,959, filed September 28, 1942, now Patent No.2,416,306 granted February 25, 1947. This demodulation, for example,preferably is of the character involving the generating or synchronizingof ian energy wave hav- Ving recurring inclined portions, the period ofwhichv is comparable to the unmodulated time The wave and the pulses arecombined, the pulses being superimposed on the wave at points along theinclined portions thereof according to thetime displacement of thepulses. This. produces by threshold. clipping output. pulse energy whichvaries in amplitude accordngy to the time modulation of the inputpulses.

In Fig. 2, a plurality of curves havingthe same time base illustratesthe operating steps of the V translator I4 and demodulator 20 when anampli- .tude modulated waveV is received. Curve 2a shows an enlargedView of a portion 2| of the carrier wave which outlines an envelope. 22,23.

'Energy of this. wave when passed through the gate' clipper i5 `isclipped between the limits 25 and 26. While I have shown these limitinglevels to bev equally spaced' on opposite sides of the axis ofthecarrier wave, it will be understood that they maybe selected to one`side or the other of the axis if' desired. The importance of thisselecvtion is` that the sides of the undulations between the limitinglevels should be such that the slopes thereof vary in substantiallylinear proportion `to the amplitude variation of the correspondingundulations.

It is preferable, therefore, that the limit', clipping operation be madenear the axis of the carrier.

4 It will' be noted that by vlimit clipping the carfri'er wave 'neartlieaxis thereof that. a large por- 4 tion of the undulations of thewave forming the envelopes is eliminated. This clipping of an amplitudemodulated Wave for translation into time modulated pulses eliminates alarge percentage of the undulations of the wave and therefore, also, toa very large extent, noise and other interfering voltage fluctuationsoccurring on the wave. The limit clipping of gategclipper i5 results ina trapezoidal wave 39, curve 2b, this portion segregated fromv the wave2| being amplified as indicated by comparison of curve 2b with theportion between levels 25 and 26 of curve 2a. It will be clear that avery small portion of modulation characteristic -of the wave 2| isretained in the. trapezoidal wave 39, the side edges thereof being thev'only "corresponding portions. 'I'he sides of the cycles 3|, 32, 33etc. of the trapezoidal wave 30, for example, vary in slope from cycleto cycle in proportion to the amplitude variations of the correspondingundulations of the carrier wave 2|. If the gateaopening of the clipperl5 is smallv compared to the unmodulated -amplitude of the carrier, thechange: in slopev of the side edges of the cycles will be a linearlfunction of the initial modulationof the carrier.

The first diiferentiator I6 translates the trapezoidal wave 39 intorectangular pulses 31a., 3|b; 32a, 32h; etc. as shown by curve 2c. Theserectangular pulses correspond in amplitude and width to the slope of thecorresponding side edges of the cycles of the trapezoidal Wave. Theserectangular pulses when applied to the second diiferentiator are-furthertranslated by producing for each such pulse two narrow positive andnegative pulses suchl as represented by the pulse pairs 4|, 42; 43, 44;45, 46; 41, 48;v 49, 59; 5|, 52; etc. of curve 2d. It will be noted thatthe rectangular pulses of curve 2c vary in amplitude andthe subsequentdifferentiation carries over this variation so that the pulses at curve2d likewise varyfin amplitude and each pair of pulses such as pulses-4|and 42 correspond in position to the leading and trailing edges of thecorresponding input pulse of curve 2c.

The pulses of curve 2d are limited by a second gate clipping by theclipper 8 between levels which may be selected on either side of theaxis of the curve and which removes the amplitude variation of the`pulses. For purposes of illustration the clipping operation is shown onthe negative side of the curve between levels 55 and 56. The clippedportions of the negative pulses are amplified bythe clipper as desiredgiving the corresponding pulses shown` in curve 2e.

The next operation `of the translator is that of blocking. For amplitudemodulated waves the blocking oscillator may be adjusted so as not tohave a blocking function if the carrier frequency is'not too high forproper operation of the demodulato'r. If the carrier frequency is toohigh, alternate pulses or groups of pulses may be eliminated whichevermay be desired. For purposes of illustration, the blocking oscillator isindicated for wave 2|4 to be` adjusted to provide a blocking periodSB-'Whic'his of a duration `such as not to interfere with theA pulseoutput ofthe clipper I8. 'As shown in curve 2f, the pulse output of theblocking oscillator I9,y and therefore the clipper IB for this example,represents a displacement by pulse pairs such as 42, 44; 46, 48; 50, 52;the intervals t1, t2 and ts of which vary substantially directlyY in,proportion to the amplitude variations of the undulations of the carrierwave 2| from which the pulses are derived. y

For-purposes'of illustrating generally one of aforesaid copendingapplication Serial No.

459,959, the pairs of pulses of curve 2e are shown4 by curve 2f to beapplied to a sinusoidal wave 60 which by proper adjustment of thedemodu-l lator may be synchronized with the unmodulated repetitionfrequency of the input pulses. It will be observed that when the pulsesare superimposed upon the wave 60 their degree of displacementdetermines the amplitude thereof with respect to the threshold clippinglevel 62. By suitable threshold clipping, the pulses may be resolvedinto pulse energy as indicated by curve 2g which Varies in amplitudeaccording to the time modulation of the input pulses and therefore inproportion to the intelligence conveyed by the input carrier wave 2|.This pulse energy of curve 2g provides an envelope as indicated at 64which after passing through a suitable filter to remove the carrierpulse harmonics may be applied to an audio amplifier and/or speaker asdesired.

In regard to the relative size and relationship of the several curves ofFig. 2 and of the Figs. 3-6, it will be appreciated that the proportionshave been selected so as to better illustrate the invention rather thanto attempt the showing of an exact reproduction of particular tests.

In curve 3a of Fig. 3, I show a portion of a frequency modulated carrierwave 1|. This wave is shown to carry signal intelligence according toline 12. For translation of the frequency modulated carrier into timemodulated impulses, the wave is passed through the translator |4 in amanner similar to that described in connection with the amplitudemodulated wave 2| of Fig. 2. The gate clipper I5 clips the wave betweenlevels 25 and 28 thereby producing a trapezoidal wave 14 as indicated bycurve 3b. As in the description of wave 2|, this clipping yeliminates toa high percentage noise and other voltage interference. The side edgesof the trapezoidal wave vary in slope in accordance with the slope ofthe sides of the corresponding undulations of the wave 1|. The steepnessofthe side edges depend directly on the period of the undulations andtherefore convey the modulation thereof.

The first differentiator i5 translates the wave 11| into rectangularpulse energy 'I5 as indicated at 3c which when further diiferentiated bythe second dierentiator I1 produces pulses 15, 8|; 11, 82; etc. asindicated by the curve 3d.

The gate clipper I8 may remain at the same adjustment as for the curve2| of Fig. 2 and thereby clip the negative pulses of curve 3d betweenlevels 55 and 56. The output of the clipper I8, as indicated by curve3e, comprises pulses 8|, 82, 83, 84, B5, 88.231,89 etc.

The blocking oscillator I9 has an important function in connection withF. M. waves since the pulses thus produced Vary in number in accordancewith the modulation. By use of the blocking oscillator proper adjustmentthereof will so eliminate pulses as to produce pulses having a constantrepetition rate and in addition a displacement characteristic closelyapproximating the modulation characteristics of the input wave 1|. Thisis obtained by adjustment of the oscillator so that the oscillator isadapted to be triggered by pulse 8|, for exam-ple, and the period ofblocking 98 initiated thereby is such as to elimilnate those pulsesfollowing pulse 8| whichfall within such period. As shown by curve 3a.the pulse 82 is eliminated bythe period 90. The next succeeding pulse'83again triggers4 theloscillator N producing'another blocking'period' 92which elininates pulse 84. The pulse again triggers theoscillatorproducing blocking period 93 which eliminates in this instancepulses 86 and 81. This blocking of two or more consecutive pulses willnot interfere appreciably with the intelligence conveyed by the train ofpulses since the signal envelope may be dened by a considerably smallernumber of pulses than will be derived according to my invention from theusual F. M. wave. Curve 3f shows the output pulses of the blockingoscillator I9 and as will be seen, the time intervals t4, t5 etc. ofsuccessive pairs 8|, 83; 85, 89 etc. vary proportionately in accordancewith the modulation of the input carrier 1|. The demodulation of thepulses of curve 3f may be carried out similarly as illustrated by curves2f and 2g of Fig. 2. It will be understood, however, that the T. M.demodulator 2|) may operate on any of the several demodulatingprinciples disclosed in my aforesaid copending vapplication Curve 4a ofFig. 4 shows pairs of pulses IDI, |812; |83, |04; etc. which conveyintelligence according to the double pulse modulation principles. Themaximum degree of displacement of the pulses is indicated by therelative positions of the two pairs of pulses shown, the displacement ofthe pulses occurring between their solid line position and their brokenline position. For example, pulse IUI may be displaced anywhere desiredbetween its present solid line position and the broken liney positionI8. Thus, the unmodulated interval of each pair of pulses is representedas the interval T. The one extreme displacement position shown by thepair of pulses IGI, |02 is represented by the interval te while theother extreme displacement interval t1 is represented by the position ofpulses |03, |04.

When the carrier wave represented by the train of pulses of curve 4a isapplied to the gate clipper I5, the clipper is preferably adjusted toclip the pulses at elevated levels such as indicated by'lines ||2 andH3. This eliminates to a large extent noise voltages occurring betweenthe pulses. The output of the clipper I5 is shown by curve 4b to be aseries of pulses lilla, |02a, |ll3a, |U4a etc. Differentiating thesepulses by diierentiator I8 produces positive and negative pulses |2|,|22; |23, |24; |25, |26; |21, |28; etc. of curve 4c. Curve 4d showsthese pulses as they appear Iafter passing through the seconddifferentiator I1, the pulses being substantially identical as in curve4c since the output of the first differentiator cornprises only thefrequency component which may the axis of the curve 4d. As shown, forpurposes of illustration, the limitsare selected at levels |3| and |32on the negative side of the curve. This produces a train of pulses inpairs |22, |24; |26, |28; etc. the relative displacement of which issubstantially identical to the displacement between the correspondingpairs of input pulses of curve 4a..

The blocking oscillator in this instance may be as described previouslyfor blocking between pulses or switched out of circuit by switch |9a sothat it Will not interfere with the pulse output of clipper I8. Thus,the pulses of curve`4e may be applied directly to the demodulator 20 inthe manner illustrated in. yconnection with carrier wave 2|, Fig.`2.

.enamore e'Curve ia' .of Fig. 5 'illustrates a' carrier wave modulatedaccording to zone form .of pulse :Width modulation. This formis ofthecharacterwhere :alternate pulses |441, |43 etc. are `xed A'in timedisplacement while the :alternate pulses |42, .|44 etc. occurringbetween the xed pulses `vary in width. `This Ypulse vcarrier Awave maylikewise be .clipped between .limits I-I2 and H3 'by clipper M5 therebyproducing -a -train of corresponding pulses I4Ia, VIZa etc. as :shown'by curve '5b.

These pulses are diierentiated by the first diferentiator .t6 to producealternatepnarrow width vpositive and negative pulses as shown 'iby curve50. .The lsecond rdiierentiating step passes the pulses of curve 5.o asshown 'by curve 5d. `The clipping operation .of gate clipper :IB may vbe'taken .between lthe Alevels I3I and 132 as in the .case `of the timemodulated .carrier of lFig. 4 thereby producing apulse energy output tasshown :by pulses ISI, |62, :|63 etc. of curve 5e. .It will be observedthat the pulse displacement interval ta l.of :the Ypair :of vpulses 16|,|62 oi vcurve 5e `correspond directly with the displacement between 4the'trailing edges of the .pair of Apulses I4I, |42

.of lcurve 5a. Likewise, displacement interval t9 :between pulses |63,|64 vcorresponds to the 'interval .between the trailing edges of pulses|43, I 44. Should the clipping be selected at levels above the axis ofcurve 5d, the intervals between the output pulses of each lpair wouldthen correspond to :the'interval 'between the leading edges of thepulses of the rcorresponding input pair.

As in the case of kthe time modulated pulses of Fig. 4, the pulse outputof gate clipper I8 for .the pulse width modulation of Fig. 5 need notutilize 'the blocking function of the oscillator I9. Therefore theoscillator may be adjusted or cut out by switch I9a so that the pulseoutput of the Iclipper :I8 is passed directly to the demodu- ,lator`21ll and the intelligence conveyed thereby demodulated 'in the usualmanner.

In curve -Sa of Fig. 6 I show a train of pulses which 'convey signalintelligence by a diierent type of pulse width variation. Pulse |10 maybe :taken Yas the minimum width pulse while pulse fI 1.3 indicates vthemaximum width to which the pulses may be varied. -Pulses IlI ,and |12vare of widths in between these two limits. This train of pulses willpass through the gate clipper "I5 and the rst and second diiferentiatorsI6 and YII to produce alternate positive and negative pulses such .asritil, '|8011 in response to each of vthe input pulses such as pulseI'Ill. When this pulse energy is applied to the second igate clipper I8,vthe clipper may be adjusted to limit the pulses between levels |88 and|89 and the .output oi the clipper may be applied through switch IfBa toconnection -I9c whereby the positive or the negative pulses, as thelcase may be, are rectified .and then mixed with the unrectied .pulsesthereby producing an output of pulses 96, |8011; 1.9i, I'Siaetc. asshown by -curve 6c.

It will be robserved that the intervals between the pulses 4of :eachpair IBO, Igllzr; ISI, Iz9la etc. are directly proportional to theWidths vofthe tcorresponding input pulses 11.0, Ill., etc. Thus, thesignal intelligence represented by the width variation vof the inputpulses is translated into double pulse modulated 4energy which may beapplied .to the demodulator and thereby ldemodulated in the usualmanner.

From .the foregoing description, it is clear that Ihaveshown severalforms of carrier waveswhich may be received and translated vfordemodulation by using common portions of `the same radio 8 receiver.'While the several parts .of `the translator may require :adjustment in.order to `obtain optimum quality -of the :intelligence conveyed lbycarrier Vwavesmodulated according to :different principles, detection-ofintelligible reception of carrier waves regardless of the Aprinciplesof modulation and many Ivariations in the transmission `characteristicsthereof, is possible by means of my receiver system without requiringiine :adjustment or tuning. The `quality of the reception, however, may'be `improved by proper tuning of -t-he dierent 4clipper stages 'andlalso Ithe blocking oscillator and demodulator stages.

It will be readily .apparent to those skilled `in the art that if itwere possible to have the dif- `ferent transmitting stations controlledaccording .to predetermined standards, that is, as to the lfrequency ofcarrier wave, repetition AVffrequeI-lcy of pulses, etc. that certain -ofthe stages of my receiver could be :adj-usted permanently and require.no tun-ing adjustment for `optimum reception. .I have reference hereparticularly to the 'blocking Aoscillator 19. and `in certain instancesthe gate :clippers I5 and I8. In view of the fact, that there .are :noset standards for the `transmission of carrier Waves yaccording to theseveral l diierent principles oi modulation, it will be-desir- -able -toprovide for tuning adjustment of the 'several stages. It Will beobserved, however, -that the gate Vclippers I5 and I-8 :may be gangedtogether for `simultaneous and 4like adjustment.

While I have shown in Eig. 3, the translation of an F. .M. carrier, itwill be observed that the pulses of curves 3c or 3d may be transmittedas the carrier from a Atransmitter the place of the wave .'I-I where itis desired :to transmit the modulation by `pulses. Should this be thecase the trains-oi pulses according to ,either curves 3c or 3d aredetectable 'by my radio receiver and translatable into T. M. pulsesys-uch .as indicated by curve 3f according to .the operating steps of`the translator feature -of imy invention. In my copending'applicationvSerial No. 488,178, led May 24, .1943, now Patent No. 2,468,062,.issued September 24, 1946, I show an .improved radio receiver fortranslation of pulses Varying in pulse repetition frequency .intodou-ble' T. M. pulses. 'The local pulse generator fea-ture in suchreceiver may be substituted for the oscillator -ISV in the presentreceiver.

While I have shown kone embodiment of my invention together with severalgraphicalillustrations of carrier waves that vmay 'be received,translated and demodulated according to the principles of my invention,it will be readily apf parent to -those skilled lin the :art that manymodications both in the method .and the operating means for translatingthe lcar-rier waves-are possible wi-thout departing from the invention.It Vis to be understood, therefore, that the illustrations hereindisclosed are Vgiven .by Way of example only and not as limiting thescope .of the .invention as set forth in the .objects .and the appendedclaims.

I claim: f f

1. A V`radio .receiver .system for .receiving carrier waves modulatedvaccording to anyone .of a plurality .of different modulating principles`comprising means to receive a carrier wave modulated according to anyone of .said principles, means to limit clip the carrier wave betweentwo limits, so that regardless -of the principle of modulation, waveenergy is segregated from said carrier vwave having a characteristic.corresponding to the modulation .of the wave, means 'to differentiatethe segregated energy to produce pulses, means to select those ofthepulses which representa train of time modulated pulses equivalent tothemodulated carrier wave, and means to demodulate said time modulatedpulses, the pulse selecting means including a blocking oscillator havingan adjustable synchronizing range forselection 'of pulses within aselected range of frequencies.

2. A radio receiver system for receivingl carrier waves modulatedaccording to any one of a plurality of different modulating principlescomprising means to receive a carrier wave modulated according to anyone of said principled-means to limit clip the carrier wave betweentwolimits, so that regardless of the principle of ymodulation, waveenergy is segregated from said carrier wave having a characteristiccorresponding to the modulation of the wave, means to differentiate thesegregated energy to produce pulses, means to ,select those of thepulses which represent a train of time modulated pulses equivalent tothe modulated carrier wave, and means to demodulate said time modulatedpulses, the pulse selecting-means including a limit clipper arranged toobtain an output of unidirectional pulses and a blocking oscillatorhaving an adjustable synchronizing range for selection of thoseunidirectional pulses within a selected range of frequencies.

3. A radio receiver system for receiving carrier waves modulatedaccording to any one of a plurality of different modulatingprinciplescomprising means to receive a carrier wave modulated according to anyone of said principles, means to limit clip the carrier wave between twolimits, so that regardless of the principle of modulation,

wave energy is segregated from said carrier wave having a characteristiccorresponding to the modulation of the wave, means to differentiate thesegregated energy to produce pulses, means to select those of the pulseswhich represent a train of time modulated pulses equivalent to the moduilated carrier wave, and means to demodulate said time modulated pulses,the pulse selecting means including a rectifier and mixer device bywhich pulses of opposite polarity are resolved into unidirectionalpulses.

4. A radio receiver system for receiving carrier Waves modulatedaccording to any one of a plurality of different modulating principlescomprising means to receive a carrier wave modulated according to anyone of said principles, means to limit clip the carrier wave between twolimits, so that regardless of the principle of modulation, wave energyis segregated from said carrier wave having a characteristiccorresponding to the modulation of the wave, means to differentiate thesegregated energy to produce pulses, means to select those of the pulseswhich represent a train of time modulated pulses equivalent to themodulated carrier wave, and means to demodulate said time modulatedpulses, the differentiating means including rst and seconddifferentiators arranged in series relation, whereby the output of thefirst diierentiator is subjected to a further differentiating operationby the second differentiator, and the pulse selecting means including alimit clipper arranged to obtain an output of pulses of selectedamplitude and a blocking oscillator having an adjustable synchronizingrange for selection of those pulses of a given polarity within aselected range of frequencies.

5. In a radio receiver system having means to receive a carrier wavemodulated according to any one of a plurality of diierent modulatingprinciples, means to limit clip the carrier wave between two limits,first and second diierentiators arranged in series relation for` resr1virf-1gf1I ui clipped wave energy into pulses-of opposite'pol'ar'- ity,a two-level gate clipper adjustable' fori-selective clipping of saidpulses,'a blocking oscillator, a by-pass connection, a rectiiier andmixer device a time modulation demodulator, and switch means forselectively connecting said` oscillator, said by-pass connection or saiddevice, between said gate clipper and said demodulator. fy 6. A systemfor translating the modulation characteristics of a carrier wavemodulated 'according to any one of a plurality of different modulatingprinciples comprising means to limit said carrier wave between twolimits, so Ythat regardless of the principle of modulation,l wave energyis segregated from said carrier wave having a characteristiccorresponding to the modulation of the input wave, means todifferentiate the segregated energy to produce pulses',l and means toselect those of the pulses whichrepresent a train of time modulatedpulses substantiallyequivalent to the modulation of the input wave, thepulse selecting means including a blocking oscillator having anadjustable synchro-- nizing range for selection of pulses within aselected range of frequencies. I

'7. A system `for translating the modulation characteristics of acarrier Wave modulated according to any one of a plurality of differentmodulating principles comprising means to limit said carrier wavebetween two limits, so'that" regardless of the principleofmodulatiomwave energy is segregated from said carrier wave hav` ing acharacteristic corresponding to the modulation of the input wave, meansto differentiate the segregated energy to produce pulses, and meanstoyselect those of the pulses which represent a train of time modulatedpulses substantially equivalent to the modulation of theinput wave, thepulse selecting means including a limit clipper arranged to obtain anoutput of unidirectional pulses and a blocking oscillator having anadjustable synchronizing' range for selection of those unidirectionalpulses within a selected range of frequencies.

8. A system for translating the modulation characteristics of a carrierwave modulated according to any one of a plurality of differentmodulating principles comprising means to limit said carrier wavebetween two limits, so that regardless of the principle of modulation,wave energy is segregated from said carrier wave having a characteristiccorresponding to the modulation of the input wave, means todifferentiate the segregated energy to produce pulses, and means toselect those of the pulses which represent a train of time modulatedpulses substantially equivalent to the modulation of the input wave, thedifferentiating means including first and second differentiators wherebythe output of the rst differentiator is subjected to a furtherdifferentiating operation by the second differentiator, and the pulseselecting means including =a limit clipper arranged to obtain an outputof pulses of selected amplitude and a blocking oscillator having anadjustable synchronizing range for selection of those pulses of a givenpolarity within a selected range of frequencies.

9. A system for translating the modulation characteristics of a carrierWave modulated according to any one of a plurality of differentmodulating principles comprising means to limit l1 ing a characteristiccorresponding to the modulation of the input wave, means to diierentiatethe segregated energy to produce pulses, and means to select those ofthe pulses which represent a train of time modulated pulsessubstantially equivalent to the modulation of the input Wave, the pulseselecting means including a limit clipper adjustable to selectively clipthe pulses, a pulse blocking oscillator, a rectifier-,mixer device, aconnection by-passing said oscillator and said device, and switch meansfor selectively connecting said limit clipper to said oscillator, saiddevice and said connection.

10. A method of translating the modulation characteristics of av carrierWave modulated according to any one of a plurality of differentmodulating principles comprising segregating a portion of the carrierwave modulated according to anyone of said principles between two limitsselected so that the segregated portion retains the modulatingcharacteristics of said carrier wave,`

diierentiating'thesegregated Wave portion to produce pulses, andselecting those pulses which represent a train of time modulated pulsessubstantially equivalent to the modulation characteristics of saidcarrier wave, the selection of pulses including a blocking operationadjustable for selection of pulses within a selected range offrequencies.

11. A method of translating the modulation characteristics of a carrierWave modulated according to any one of a plurality of diierentmodulating principles comprising segregating a portion ofthe carrierwavemodulatedaccording to any one of saidv principles between two limitsselected so that the segregated portion retains the modulatingcharacteristics of said carrierwave, differentiating the segregated Waveportion to produce pulses, and selecting those pulses which represent atrain of time modulated pulses substantially equivalent to themodulation lcharacteristics` of saidV carrier wave. the selection ofpulses including a limit clipping operation to obtain an output ofpulses of selected amplitude and a blocking operation. adjustable forselection of those pulses of a given polarity .occurring Within aselected range of frequencies.

12. A method of ...trans1ating ,the modulation characteristics of acarrier Wave modulated according to any one of a plurality of diierentmodulating principles comprising segregating a portion of the carrierwave modulated according to any one of said principles between tWolimits selected so that the segregated portion retains the modulatingcharacteristics of said carrier Wave, diierentiating the segregated Waveportion to produce pulses, and selecting those pulses which represent atrain ,of time modulated pulses substantially equivalent to themodulation characteristics of said carrier Wave, the selecting operationincluding blocking a substantial portion of the time intervals betweensuccessive ones of the selected pulses.

DONALD D. GRIEG.

REFERENCES CITED The following references are of recordin the ille ofthis patent:

UNITED sTATEs vPirrnirrs Grieg Apr. 29, 1947

